Friday 13 August 2010 19.05 EDT
First published on Friday 13 August 2010 19.05 EDT

In the months after the end of the first world war, some 40 million people died amid a worldwide flu pandemic. Three million perished from typhus; five million Ukrainians starved to death. No more battles, but no food, no medicine, no shelter, no resistance, either: just milling chaos. The fighting had ended, but its baleful, destructive legacy lingered on. And the question for the western allies, immersed in another world war some 25 years later and brooding on consequences long before Hitler admitted defeat, was whether they could do better second time round.

Ben Shephard sets out to provide the answers of formidably researched history. He can't pull every strand together: there were millions of human stories. The challenge to the embryo "world community" of allied concern and its chosen solution, UNRRA – the United Nations Relief and Rehabilitation Administration – was likewise immense and infernally complex. For not everybody wanted to go home – or even knew where their true homes were.

UNRRA's tally of "displaced persons" included Poles, Ukrainians, Balts, Russians and many more who'd kept Hitler's factories turning as Germany ran short of infantry to hold the frontline. Some were forced labour, some willing volunteers. Some were happy enough to go back to Poland, some would do anything to avoid living under encroaching Soviet communism. Ukraine, then as now, was split two ways, one side looking east, the other west. The Balkan states were their usual mess. Italians, once Mussolini departed, proved neither friends nor foes, but a burden. Germans driven from their farms in Poland and Czechoslovakia flocked to find safety in their beaten, battered fatherland. And then, of course, there were the Jews.

In part, but only in part, Shephard charts the founding of Israel and, fascinatingly, sets it in a context few politicians (or readers) would recognise six decades on. How did UNRRA deal with the horror of the Holocaust? It didn't. Nobody in the 40s talked about holocausts. One Fabian Society report managed half a paragraph mentioning two million Jewish deaths in 26 pages examining Europe's displaced persons.

There was the casual antisemitism of General George Patton as his conquering army scythed across Europe. The Jews he found and freed were, he declared, "lower than animals". There was, still more surprisingly, an antipathy in the White House that would set Washington imploding today. "The Jews," President Truman wrote in his diary, "are very, very selfish. They care not how many Estonians, Latvians, Poles, Yugoslavs or Greeks get murdered or mistreated as long as the Jews get special treatment. Yet when they have power, physical or political, neither Hitler nor Stalin has anything on them for cruelty or mistreatment of the underdog."

Shephard's strongest suit as he chronicles these and other explosions of frustration or prejudice is that he leaves in all the raw edges and profound contradictions of the shattered world of the 40s; he doesn't try to smooth them into some conventionally heroic narrative. Remember, Harry Truman was also the most powerful friend of Israel's creation. Patton reflected a widely prevailing opinion in top US military circles (and, frankly, much of US society). Britain's sometimes saintly Labour government struggled might and main to fob off David Ben-Gurion and keep Chaim Weizmann's softer brand of Zionism in time-consuming diplomatic play.

Establishing UNRRA might have been an international deed of foresight and wonderfully high intentions (with FDR, as so often, in the van), but good intentions didn't run to giving the administration either the leadership or money it needed. Too many average bureaucrats and below-average politicians got seats and desks as the crisis of the peace began. Too many supposedly benevolent nations – asked to take their share of the 1.5 million dispossessed no one wanted – answered the call without any enthusiasm.

"Give me your tired, your poor, your huddled masses" read the words on the Statue of Liberty. But the laws passed on Capitol Hill were quite different: keep the huddled masses away. America already had strict immigration legislation and tough, inflexible quotas. Public opinion in 1945 was resolutely against easing such rigidities. Truman was a hero here, leading where he could have lain low, taking risks, even telling George Marshall he could claim the credit for the master plan that helped to rescue Europe because a "Truman Plan" would never make it through the Senate.

Just as dismayingly, the British, left as well as right, did not leap to help the homeless or defenceless. "Let them be Displaced," said the Daily Mirror, complaining we'd taken in "most of the scum" from Europe and given others the cream. We don't want the "illiterate, the mentally deficient, the sick, the aged, the politically suspect and behaviourally disruptive" working here, said the New Statesman. And yet slowly, patiently, sometimes with judgment, often with luck, the problem was solved – or at least moved on to another stage and another generation.

Shephard does not seek to draw pat lessons or modern conclusions from any of this. He is content to tell us what happened next, in detail, and often vividly. But you can't read The Long Road Home without jolts of sudden relevance – whether of political frailty, electoral insularity, or from registering the basic factors, such as existing immigrant communities to join up with, that make some migrations far more successful than others.

A good story or a bad one for mankind? In the end, more good than bad – but full of awful warnings. And, from Shephard, a riveting and often entirely fresh story, shrewdly assembled, very well told.